The present disclosure generally relates to evaporative emission control systems (e.g., for internal combustion engines), and more particularly relates to a microcondenser device for evaporative emission control and evaporative emission control systems and methods incorporating microcondenser devices.
Conventional vehicle fuel systems associated with internal combustion engines typically employ a fuel canister for receiving fuel vapor from a vehicle's fuel tank. The fuel canister is adapted to temporarily retain the received vapor therein to prevent it from being released to the atmosphere. More particularly, fuel vapor can enter the fuel canister from the fuel tank wherein the fuel vapor is absorbed and retained in a carbon bed of the fuel canister. Typically, the retention of the displaced fuel vapor within the fuel canister is only temporary as the fuel vapor retained in the fuel canister is periodically purged to allow the canister to accommodate and absorb additional fuel vapor from the fuel tank. During such purging, the fuel vapor captured by the canister can be sent to the vehicle's engine, and particularly to an induction system of the engine, for combustion.
Various other systems have been proposed to more strictly control containment of fuel vapors and/or improve vehicle efficiency by controlling fuel vapor processing. Some of these systems can be used in environments beyond that of a vehicle (e.g., underground fuel storage vessels). For example, some systems include a bladder disposed in a vehicle's fuel tank that expands and contracts to control fuel vapor. A pump can be used in association with the bladder for applying pressure to the walls of the bladder. The pressure is applied for purposes of forcing the bladder walls against the fuel contained therein to prevent or limit vapor formation. A fuel canister, as described in the preceding paragraph, can optionally be used in the bladder fuel system for capturing fuel vapor that forms despite the use of the bladder.
Also known is a canisterless evaporative emission control system for an internal combustion engine. One particular known system includes a fuel tank wherein vaporized fuel is generated and a microcondenser device for processing the vaporized fuel received from the fuel tank. The microcondenser device has a heat sink portion formed of carbon foam in thermal communication with a thermoelectric element for removing heat from the heat sink portion. The fuel vapor is processed by passing the fuel vapor through the heat sink portion to remove heat therefrom and condense at least a portion of the fuel vapor to liquid fuel. Drawbacks of this known canisterless control system include significant power consumption requirements for the thermoelectric element and a significant volume of uncondensed fuel vapor passing through the microcondenser device.